Monument Valley Home Page
Monument Valley Navajo Tribal Park (29,817 acres, elevation of 5,564 feet)
is not a valley at all, but rather a wide flat, landscape interrupted by
colorful red buttes and spires rising hundreds of feet into the air. These
are the last remnants of the sedimentary rock layers that once covered the
entire region. Monument Valley is contained entirely within the Navajo
reservation, occupying both Utah and Arizona. This is one of the most
remarkable, beautiful and famous landscapes in the world, early recognized
by Hollywood as a stunning background for western films. A painting of
this region is majestically portrayed as the sole mural in the Smithsonian
Space and Science Museum.

Geology of Monument Valley
Monument Valley sits atop the crest of a wide anticline, the Monument
Upwarp. These beautiful layers of sandstone were formed from deposits of
an ancient sea covering much of western USA. The siltstone and shale were
deposited here in ancient times and were buried for millennia until, like
the rest of the Colorado Plateau, it was uplifted and folded. The reddish
hues in the sand and rock of the valley are due to iron oxide; the black
streaks of desert varnish are manganese oxide. Eroded by wind and rain,
soft red shale undermines the stronger, vertically-jointed sandstone,
producing the many buttes and pinnacles. The buttes and pinnacles of
Monument Valley are composed of Permian-age (270 million years ago) Cedar
Mesa Sandstone. The slopes at their bases are usually composed of Halgaito
shale, while many of the spires have cap rocks of red Organ Rock shale,
also from the Permian period. Volcanic activity subsequently
occurred in areas surrounding the Uplift, releasing molten rock from
underneath. The only remnants of the many volcanoes are the hardened cores
whose scattered silhouettes tower in the distance (Agathla Peak and
Alhambra Rock).